Developments in wind energy plants to be erected inland are leading to ever higher hub heights of above 100 m in order to utilize greater and more constant wind speeds and thus to improve the efficiency of these wind energy plants. However, higher tubular towers having larger and more powerful rotors and generators require at the same time an increase in the wall thicknesses and diameters of the tower segments in order to meet the greater structural-mechanical demands that result therefrom, such as rigidity, protection against buckling and fatigue strength. However, the increase in the diameters of the tower segments also results in it no longer being possible to transport the prefabricated tubular tower segments with the conventional transversely oriented construction type on many roads on account of restrictions, for example bridge clearance heights of 4.4 m.
A possible solution, which is proposed for example in DE 603 17 372 T2 and also in WO 2009/048955 A1, is what is referred to as the longitudinally oriented construction type, in particular in the lower tower region, in the case of which the diameters of the finished tubular tower segments are ultimately more than 4.4 m. In this case, tubular tower sections are first put together from a plurality of arcuate shell segments at the construction site, i.e. at the location of the wind turbine, and the tubular (annular) tower segments produced in this way are connected to form the overall tower. In order to avoid welding at great heights, the shell segments in the tower construction known from DE 603 17 372 T2 are provided with perforated horizontal and vertical flanges which allow the shell segments to be connected by screws. However, this solution has a number of disadvantages. For example, in the case of large shell segments, deformations are to be expected on account of the dead weight of the shell segments, it being possible for said deformations to result in handling or fitting problems during assembly. On the other hand, in the event of subdivision into a large number of small shell segments, the number of screwed connections to be produced is relatively high, thereby increasing the assembly and also maintenance costs for re-tightening the screws.
In addition to wind power plants having a tubular tower and wind power plants having a lattice tower (truss tower), wind power plants having towers with a hybrid construction type, which have a lower lattice tower (truss tower) and an upper tubular tower connected thereto, are also known. DE 10 2006 056 274 A1 discloses a tower of the type mentioned at the beginning, which has a lattice tower with at least three corner bars in its lower part and a cross-sectionally round tubular tower in its upper part, wherein the upper connection region of the lower part is connected to the lower connection region of the upper part by means of a transition body in the transition region. The transition body is in this case formed in a manner of a truncated conical casing, wherein the corner bars extend into the transition region and are at least sectionally welded to the truncated conical casing in the transition region between the upper connection region of the lower part and the lower connection region of the upper part. The lattice tower has intersecting struts which connect the corner bars of the lattice tower together. The corner bars of the lattice tower are formed from standardized hollow profiles, preferably from steel tubes.